At present, when an output voltage of a DC-DC converter is switched from a high supply voltage to a low supply voltage, the problems of the too long switching time and the high energy loss tend to occur so that a post-stage circuit cannot be rapidly driven and the energy cannot be saved.
A conventional DC-DC converter provides an additional grounding path to transfer the excess energy to the ground and thus shorten the time of switching from the high supply voltage to the low supply voltage. However, the electric energy transferred to the ground also wastes the energy. Thus, it is an issue to enhance the switching speed and save the energy.